Seat System: Diagnosis Chevrolet Silverado 1500

DIAGNOSTIC CODE INDEX

DIAGNOSTIC CODE INDEX

Diagnostic Starting Point - Seats

Begin memory and heated seat system diagnosis with Diagnostic System Check - Vehicle in Vehicle DTC Information.

The Diagnostic System Check will provide the following information.

1. Identification of the control modules that command the system.
2. The ability of the control modules to communicate with a serial data circuit.
3. Identification of stored diagnostic trouble codes and their status.

The use of the Diagnostic System Check will identify the correct the correct procedure for diagnosing the system and where the procedure is located.

Scan Tool Data List

Driver Seat Module

Driver Door Module

Passenger Door Module

Circuit Description

The seat adjuster motors are controlled by the driver seat module (DSM) through the adjuster motor control circuits. In an inactive state both of the motor control circuits are grounded within the DSM. In an active state the DSM switches the appropriate motor control circuit to battery positive voltage. The direction of the adjuster motor rotation is determined by which of the motor control circuits is switched to battery positive voltage while the other remains grounded. During adjuster motor operation the DSM also monitors the current flow through the motor control circuits.

DTC Descriptors

This diagnostic procedure supports the following DTCs

1. DTC B1770 Driver Seat Motor Horizontal Circuit
2. DTC B1775 Driver Seat Motor Front Vertical Circuit
3. DTC B1780 Driver Seat Motor Rear Vertical Circuit
4. DTC B1785 Driver Seat Motor Recline Circuit
5. DTC B1790 Driver Seat Motor Lumbar Circuit
6. DTC B1805 Driver Seat Motor Side Bolster Circuit

Conditions for Running the DTC

The system voltage must be between 9-16 volts.

Conditions for Setting the DTC

The motor control circuit monitored by the DSM is determined to be shorted to ground, battery positive voltage, or open.

Action Taken When the DTC Sets

1. The seat motor with a current status DTC will be disabled.
2. When the fault is no longer present a history status DTC will be stored, and motor operation will be restored.

Conditions for Clearing the DTC

1. The DTC will be current for as long as the fault is present.
2. When the fault is no longer present the DTC will be a history status code.
3. The history DTC will be cleared after 100 error free ignition cycles, or by using the scan tool clearing DTCs feature.

Diagnostic Aids

When an adjuster motor control circuit is shorted to ground the DSM will also set a DTC B3962.

DTC B1770, B1775, B1780, B1785, B1790, B1805, or B2415

The seat recline motor is equipped with a potentiometer type position sensor used by the driver seat module (DSM) to determine the position of the seat back. The motor position sensor is supplied with 5-volt reference and ground circuits from the DSM. The position sensor signal circuit is referenced from ground within the DSM. The signal voltage monitored by the DSM ranges from 0.39-4.58 volts and is determined by the wiper location on the resistor within the motor position sensor. The position sensor circuit voltage level is used by the DSM to determine the position of the seat back when storing or recalling memory position settings.

DTC Descriptor

This diagnostic procedure supports the following DTC

DTC B1825 Driver Seat Recline Position Sensor Circuit

The system voltage must be between 9-16 volts.

The recline motor position sensor signal circuit voltage level to the DSM is not within the 0.39-4.58 volt range.

The recline motor will not function during memory or exit position recall operation.

1. The DTC will be current for as long as the fault is present.
2. When the fault is no longer present the DTC will be a history status code.
3. The history DTC will be cleared after 100 error free ignition cycles, or by using the scan tool clearing DTCs feature.

A short to voltage on a sensor signal circuit or an open ground may effect other sensors using common 5-volt reference and ground circuits causing the following DTCs to set

1. B2435
2. B2440
3. B3606

The driver seat module (DSM) monitors the positions of most of the seat adjuster motors using hall effect type position sensors. The hall effect position sensors are supplied with battery positive reference and ground circuits from the DSM. The position sensor signal circuits are supplied battery positive voltage through a resistor then monitored within the DSM. During adjuster motor operation the hall effect position sensor provides a single pulse for every adjuster motor shaft rotation. The DSM counts the pulses from the position sensor signal circuits to determine the adjuster motor positions when storing or recalling memory seat position settings.

This diagnostic procedure supports the following DTCs

1. DTC B1850 Driver Seat Lumbar Position Sensor Circuit
2. DTC B1960 Driver Seat Side Bolster Position Sensor Circuit
3. DTC B2355 Driver Seat Front Vertical Position Sensor Circuit
4. DTC B2365 Driver Seat Rear Vertical Position Sensor Circuit
5. DTC B2375 Driver Seat Horizontal Position Sensor Circuit

The system voltage must be between 9-16 volts.

The DSM does not detect position sensor movement during adjuster motor operation.

1. The affected seat adjuster motor will operate approximately 1 revolution and stop each time the adjuster switch is activated.
2. The memory recall functions for the seat motor with a current status DTC will be disabled.
3. When the fault is no longer present a history status DTC will be stored, and memory operation will be restored.

1. The DTC will be current for as long as the fault is present.
2. When the fault is no longer present the DTC will be a history status code.
3. The history DTC will be cleared after 100 error free ignition cycles, or by using the scan tool clearing DTCs feature.

The driver and passenger seat heaters are controlled by the driver seat module (DSM). Power is supplied to the driver seat cushion and back heater elements through individual voltage supply circuits. Power is supplied to the passenger seat cushion and back heater elements through a common voltage supply circuit. All of the driver and passenger seat heater elements are grounded by the DSM through individual low side drive control circuits. The heater element control circuits are pulse width modulated to ground by the DSM in order to control the seat temperatures by regulating the current flow through the heater elements.

This diagnostic procedure supports the following DTCs

1. DTC B2425 Driver Seat Heater Circuit
2. DTC B2430 Passenger Seat Heater Circuit

The system voltage must be between 9-16 volts.

The DSM determines by monitoring the heater element control circuits that a short to voltage, short to ground, or open condition exists.

1. The heated seat with a current status DTC will be disabled.
2. Both heated seats may be disabled.
3. When the fault is no longer present a history status DTC will be stored, and heated seat operation will be restored.

1. The DTC will be current for as long as the fault is present.
2. When the fault is no longer present the DTC will be a history status code.
3. The history DTC will be cleared after 100 error free ignition cycles, or by using the scan tool clearing DTCs feature.

DTC B2425 or B2430

The driver seat module (DSM) relies on inputs from thermistors located in the driver and passenger seat backs to control heated seat temperatures. The thermistors are 2 wire sensors supplied with a 5-volt referenced signal circuit and low reference circuit from the DSM. Resistance through the thermistors varies with temperature causing the heated seat sensor signal circuit voltage levels to decrease as the seat back temperatures rise.

This diagnostic procedure supports the following DTCs

1. DTC B2435 Driver Seat Back Heater Sensor Circuit
2. DTC B2440 Passenger Seat Back Heater Sensor Circuit

1. The system voltage must be between 9-16 volts.
2. The heated seat is in an active state.

1. The heated seat sensor signal circuit voltage to the DSM is greater than 4.94 volts for 30 seconds or more.
2. The heated seat sensor signal circuit voltage to the DSM is less than 0.078 volts for 30 seconds or more.
3. The heated seat sensor signal circuit input to the DSM indicates that the desired seat temperature has not been reached within 30 minutes after activation.

1. The heated seat with a current status DTC will be disabled.
2. When the fault is no longer present a history status DTC will be stored, and heated seat operation will be restored.

1. The DTC will be current for as long as the fault is present.
2. When the fault is no longer present the DTC will be a history status code.
3. The history DTC will be cleared after 100 error free ignition cycles, or by using the scan tool clearing DTCs feature.

The driver and passenger seat heaters are controlled by the driver seat module (DSM). Power is supplied to the driver seat cushion and back heater elements through individual voltage supply circuits. Power is supplied to the passenger seat cushion and back heater elements through a common voltage supply circuit. All of the driver and passenger seat heater elements are grounded by the DSM through individual low side drive control circuits. The heater element control circuits are pulse width modulated to ground by the DSM in order to control the seat temperatures by regulating the current flow through the heater elements.

This diagnostic procedure supports the following DTC

DTC B3941 Front Seat Heaters Circuit

The system voltage must be between 9-16 volts.

The DSM determines that one of the seat heater element voltage supply circuits is shorted to ground.

1. Both heated seats will be disabled.
2. When the fault is no longer present a history status DTC will be stored, and heated seat operation will be restored.

1. The DTC will be current for as long as the fault is present.
2. When the fault is no longer present the DTC will be a history status code.
3. The history DTC will be cleared after 100 error free ignition cycles, or by using the scan tool clearing DTCs feature.

DTC B3941

The seat adjuster motors are controlled by the driver seat module (DSM) through the adjuster motor control circuits. In an inactive state both of the motor control circuits are grounded within the DSM. In an active state the DSM switches the appropriate motor control circuit to battery positive voltage. The direction of the adjuster motor rotation is determined by which of the motor control circuits is switched to battery positive voltage while the other remains grounded. During adjuster motor operation the DSM also monitors the current flow through the motor control circuits.

This diagnostic procedure supports the following DTC

DTC B3962 Seat Motors Over Current

The system voltage must be between 9-16 volts.

A motor control circuit current monitored by the DSM is determined to be shorted to ground.

1. The DSM will disable the affected adjuster motor.
2. When the fault is no longer present, a history DTC will be stored in the DSM and motor operation will be restored.

1. The DTC will be current for as long as the fault is present.
2. When the fault is no longer present the DTC will be a history status code.
3. The history DTC will be cleared after 100 error free ignition cycles, or by using the scan tool clearing DTCs feature.

When an adjuster motor control circuit is shorted to ground the DSM will also set a DTC for the affected motor.

DTC B3962

Symptoms - Seats

1. Perform the «Diagnostic System Check - Vehicle»(ref-238177-S28692454672006072400000) in Vehicle DTC Information, before using the symptom tables in order to verify that all of following are true: There are no DTCs set. The control modules can communicate via the serial data link.
2. Refer to the following system descriptions in order to familiarize yourself with the system functions: «Power Seats System Description and Operation»(ref-238199-S18757607362006072400000) «Lumbar Support Description and Operation»(ref-238199-S37899970152006072400000) «Heated Seats Description and Operation»(ref-238199-S04450725172006072400000) «Memory Seats Description and Operation»(ref-238199-S04376510852006072400000)

Visual/Physical Inspection

1. Inspect for aftermarket devices which could affect the operation of the power seat. Refer to «Checking Aftermarket Accessories»(ref-238178-S36192588272006072400000) in Wiring Systems.
2. Inspect the easily accessible or visible system components for obvious damage or conditions which could cause the symptom.

Symptom List

Refer to a symptom diagnostic procedure from the following list in order to diagnose the symptom

1. «Power Seat Inoperative (with Memory)»(ref-238199-S14670010282006072400000) or «Power Seat Inoperative (w/o Memory)»(ref-238199-S31163696432006072400000)
2. «Power Seat Does Not Move Forward/Rearward (with Memory)»(ref-238199-S18240270892006072400000) or «Power Seat Does Not Move Forward/Rearward (w/o Memory)»(ref-238199-S21571699922006072400000)
3. «Power Seat Does Not Tilt Forward (with Memory)»(ref-238199-S24208005482006072400000) or «Power Seat Does Not Tilt Forward (w/o Memory)»(ref-238199-S38353468222006072400000)
4. «Power Seat Does Not Tilt Rearward (with Memory)»(ref-238199-S17740911102006072400000) or «Power Seat Does Not Tilt Rearward (w/o Memory)»(ref-238199-S39985802152006072400000)
5. «Power Seat Does Not Recline (with Memory)»(ref-238199-S38805589632006072400000) or «Power Seat Does Not Recline (w/o Memory)»(ref-238199-S02967169902006072400000)
6. «Memory Seat Feature Inoperative»(ref-238199-S15965551522006072400000)
7. «Lumbar Support Inoperative (with Memory)»(ref-238199-S21932044172006072400000) or «Lumbar Support Inoperative (w/o Memory)»(ref-238199-S16538834482006072400000)
8. «Heated Seat Always On»(ref-238199-S24040300872006072400000)
9. «Heated Seat Inoperative»(ref-238199-S40422133062006072400000)